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Drafting and the Writing Process - Student Handout
No full textThis guide is about the process of writing and drafting an academic paper. It includes instructions and advice on how to write a paper
Linking Individual Behavior to Population Dynamics: Insights for Effective Raven Management
No full textThe expansion of human infrastructure has altered ecosystems worldwide. Anthropogenic changes to the landscape reshape wildlife populations by influencing survival, reproduction, dispersal, connectivity, and predator-prey interactions, causing some wildlife populations to decline while enabling others to thrive and expand their range. Predatory species that benefit from anthropogenic features, known as synanthropic species, can further impact declining prey populations. The common raven (Corvus corax) is an example of such a predator. From 1966¬¬¬–2018, raven populations increased by 1.5% annually across North America. As generalist predators, ravens thrive in human-altered landscapes. As a result, anthropogenic subsidies can lead to high raven densities, ultimately having negative impacts on prey, including species of concern. Predation of these already declining populations requires effective management of raven populations. In this dissertation, I applied novel approaches to understand raven demographics and the mechanisms driving changes in raven abundance and space use.In Chapter 1, I employed a reaction-diffusion model to predict raven density across the western United States and quantify the effects of anthropogenic development on raven dispersal. My results indicated that raven abundance doubled in fewer than 2 decades (2001–2019) with hotspots of raven density in southern California, central Nevada, and northern Utah. I also identified low elevations as a driver of longer raven residence times and find moderate evidence that high road density also contributed to residence times. As ravens expand eastward, areas with these attributes may be particularly susceptible to high raven densities. By identifying areas prone to raven settlement and high densities, raven density projections provide valuable guidance for ongoing monitoring of habitat conditions, as well as raven and prey populations, which are both crucial for effective management. In addition, my results indicated that raven management in these areas might require actions beyond raven removal, as other ravens may continue to move in and settle.
In Chapter 2, I developed a mechanistic movement model to provide estimates of age-specific breeding propensity and apply it to a raven population in northern Nevada. Movements of breeding ravens were generally less diffuse and demonstrated a stronger mean-reverting tendency than non-breeding ravens, indicating that breeding ravens concentrated movement in a smaller area close to their respective nests. My results also indicated that adult ravens (≥5 years old) in the region had a breeding propensity of 0.71 (95% CRI = 0.35–0.95) and subadult (3–4 years old) breeding propensity had a breeding propensity of 0.38 (95% CRI = 0.14¬–0.67). This suggests that 29% of adults and 62% of subadults in the central Nevada population were not breeding, despite being sexually mature. Sexually mature, non-breeding individuals can buffer breeder mortality by quickly filling vacant territories and stabilizing reproductive density or acting as a source of future breeders for neighboring populations. In areas with a high proportion of mature, non-breeding ravens, management of the breeding population may not be sufficient to control raven densities.
In Chapter 3, I compared breeding and non-breeding raven space use using 3 metrics: step length, home range size, and core area size. I also compare habitat selection within home ranges between individuals of different reproductive classes. Breeding ravens had shorter step lengths than non-breeding ravens (μ = −793.41 m/hr, 95% CRI = −879.49–−703.24 m/hr). Although I did not find a difference in home range size between reproductive classes, my results indicated that breeding ravens had a smaller mean core area size, (μ = −268.73 km2, 95% CRI = −355.30–−189.96 km2). Ravens in both breeding classes selected high normalized difference vegetation index (NDVI) and low annual grass and shrub cover. However, non-breeding ravens concentrated activity near forest edges, natural water sources, and anthropogenic features, whereas breeding ravens focused activity close to their nests. These results suggest that raven management could be most effective in areas with high NDVI and annual grass and shrub cover, especially in anthropogenically modified landscapes and near forest edges. In addition, preventing the establishment of raven nests near prey populations could benefit species of concern.
The research contained in this dissertation advances scientific understanding of the raven behavior and demographics driving abundance patterns. At a landscape level, low elevations and high road densities result in ravens spending more time and possibly establishing territories in these areas. Sexually mature, non-breeding ravens not only contribute to higher raven densities in these areas, but can also act as a buffer for breeding raven mortality. Sexually mature, non-breeding ravens can also maintain high raven densities in areas with abundant resources that lack nesting sites. Furthermore, behavioral differences between non-breeding ravens and breeding ravens contribute to variation in predation intensity, with breeding ravens concentrating foraging around their nest and non-breeding ravens gathering at forest edges, natural water sources, and anthropogenic features throughout their home range. Finally, the methods I develop and employ in this dissertation not only inform raven management but can also contribute to the management and conservation of species in other systems that have similar predator-prey dynamics
The Role of the Medical Education Learning Specialist in Preparing Medical Students for the USMLE Step 1
No full textThe number of medical professionals in the United States is predicted to decrease, significantly impacting the public’s access to quality care. One possible solution is to increase the number of medical school graduates. Medical students are required to pass two parts of the United States Medical Licensing Examination (USMLE) to graduate from medical school. Since 2022, the pass rates for the USMLE Step 1 have been declining. This decline in pass rates has contributed to a decrease in medical school graduates. Medical education learning specialists (MELS) are academic support professionals who assist students throughout medical school and the USMLE; however, there is very little research on how medical schools aid students in preparing for the USMLE Step 1, and even less research on the role of MELS in that preparation. This study used a qualitative research design to conduct semistructured interviews with seven MELS at different U.S.-based medical schools. Participants discussed their roles and described the learning strategies they recommend to students preparing for the USMLE Step 1. They identified the use of data in assessing student preparedness and predicting their trajectory for completing the USMLE Step 1 in the allotted time, discussed the modes of communicating information to students, and described the specific study management, learning, test-taking, and well-being strategies they recommend. The results of this study contribute to the knowledge base of MELS and their role in preparing students for the USMLE Step 1. These findings may inform institutional support strategies and future research on the role of MELS and best practices in preparing students for the USMLE Step 1
Implicit Relational Assessment Procedure and Q Methodology: Measurement of Choice Behavior and Sensitivity to Partner Error In An Analog Work Setting
No full textHigh Reliability Organizations (HROs) in healthcare, oil extraction, and aviation require adaptability to changing conditions where appropriate responses can prevent catastrophic failures resulting in casualties and environmental damage. Integrating artificial intelligence (AI) systems can enhance HRO teamwork efficiency when properly implemented. This study investigated how individuals’ history of interaction with AI or human partners influences their choices between these partners in collaborative work contexts. Using a behavior analytic framework that considers individual history as one of the factors affecting current choice behavior, we examined whether participants’ history—measured by the Implicit Relational Assessment Procedure (IRAP) and Q methodology—could predict partner selection and responsiveness to errors. Through a simulated healthcare task, participants made choices between AI and human partners for assistance in a recurring manner. Findings demonstrated that IRAP and Q tools successfully identified aspects of participants’ history that corresponded with their partner choice behavior. Participants showed lower switching rates after errors from their preferred partner type, indicating persistent choice patterns despite partner’s performance errors. These results may provide value adding guidance for HROs seeking to optimize human-AI collaboration. Moreover, understanding how people’s history relates to partner selection and error responsiveness can inform organizational interventions and team composition strategies
Balancing Practicality and Field Relevance: A Laboratory Aging Protocol for Asphalt Surface Mixtures in Virginia
No full textAsphalt mixtures are critical to the construction and longevity of flexible pavements due to their favorable mechanical properties, ease of maintenance, and recyclability. However, they are inherently prone to cracking over time as a result of oxidative aging, traffic loading, and environmental exposure. To ensure long-term durability, it is essential to simulate and evaluate the aging behavior of asphalt mixtures through appropriate laboratory protocols. Long-term oven aging (LTOA) methods are designed to replicate field aging conditions and assess cracking resistance, but existing procedures often lack practicality or fail to capture performance variability across mixtures.This study presents a five-phase experimental framework to establish a practical and performance-based LTOA protocol for dense-graded surface mixtures used in Virginia. Phase 1 involved a mini-study on three laboratory-produced mixtures to determine a reduced LTOA duration at 95°C that reflects long-term field aging. Phase 2 expanded the analysis to ten mixtures aged at both reduced 95°C and compaction temperatures to determine equivalent aging durations and identify a practical LTOA method. Phase 3 utilized the Glover-Rowe parameter (GRP) to define CT Index thresholds for different levels of cracking severity. Phase 4 compared long-term performance under design and production conditions, identifying reheating-induced aging trends. Finally, Phase 5 incorporated FlexPave simulation and substitute-binder evaluations to assess the influence of binder quality on fatigue cracking over a 10-year period. The study recommends a practical LTOA protocol of 6 hours at compaction temperature for design, supported by strong correlations between the CT Index and binder rheological and chemical properties. A preliminary CT Index threshold of 55 is proposed for both design and production evaluations. Additionally, the study identifies 2 hours of aging after reheating and 4 hours of aging for non-reheat conditions as suitable LTOA durations during production. These findings offer a comprehensive and implementable approach for improving cracking performance evaluation within Balanced Mix Design (BMD) specifications in Virginia
The Contemporary Pianist’s Toolkit: Reimagining the Piano’s Sonic Identity Through Extended Techniques
No full textThis dissertation explores the transformation of piano performance through extended techniques that have essentially redefined the instrument outside its conventional role as a keyboard-centered instrument. Through an analysis of approaches such as playing on the strings directly, unorthodox techniques, and incorporating objects externally, this study investigates how contemporary pianists engage with sound as raw material rather than merely interpreting notes. Drawing on the contributions of Henry Cowell, John Cage, George Crumb, Curtis Curtis-Smith, and Helmut Lachenmann, the research categorizes these techniques and contextualizes them within a broader aesthetic shift, where timbre, resonance, and physical interaction with sound take precedence over traditional performance practices. These innovations have greatly enriched the possibilities of the piano’s sonic potential, challenging traditional performance and compositional approach. Beyond historical and technical analysis, this study bridges performance and composition, offering a structured framework that helps both pianists and composers understand and utilize extended techniques. For the performers, it addresses the problems in incorporating these methods into practice, and for the composers, it opens up new sonic possibilities. Furthermore, the results are relevant not only for piano performers but also for other instrumentalists who are interested in experimental approaches to sound production. Ultimately, this dissertation shows that contemporary music is still a developing field and that the divide between sound production, composition, and performance is growing blurred, leading to new possibilities in artistic creation
Exploring the Spin Density and Electrochemical Properties of Benzotriazinyl Radicals: Advancement in Functional Materials for Flow Battery Application
No full textAbstract: Redox flow batteries (RFBs) are charge storage devices that are particularly well-suited for grid-scale energy storage due to their long-life span, independent scalability of power and energy, enhanced safety compared to other battery technologies, ability to handle a large number of charge-discharge cycles without significant degradation, and potential for cost-effectiveness at large scales. The dominant material for redox flow batteries is based on inorganic vanadyl salts, which provide large cell voltages and excellent fatigue resistance. Redox-active organic compounds are promising alternatives to traditional inorganic redox-active compounds for redox flow battery (RFB) applications due to their tunable electrochemical properties through molecular design and synthesis, as well as their potential for faster charge-discharge kinetics. Stable organic radicals have come to the forefront of this field, in which fully reversible electrochemical processes are often observed. Benzotriazinyl radicals are unique materials for redox flow battery (RFBs) applications owing to their bipolar redox chemistry which arises from the ability to undergo fully reversible reduction and oxidation processes. Previous work suggests that benzotriazinyls are promising for redox flow batteries, but challenges arise in increasing the cell voltage. In this work, we report the design, synthesis and characterization of a series of 6-position functionalized 1,3-diphenyl-1,2,4-benzotriazinyl radicals (6-X-BTR, where X = H, Cl, CH3, NH2, NO2, and OMe) toward the aim of increasing cell voltage and charge/discharge kinetics. The electronic structures of the 6-X-BTR series were characterized by electronic absorption spectroscopy, electron paramagnetic resonance (EPR), cyclic voltammetry (CV), computational methods, and, for some of the series, single-crystal X-ray diffraction (SCXRD). Cyclic voltammetry confirmed reversible reduction and oxidation processes for all stable radical derivatives, revealing tunable redox potentials and moderate cell voltages (~1.0 V). Electron-withdrawing substituents (e.g., –Cl and –NO₂) were found to stabilize the radical anion forms, as indicated by anodically shifted reduction potentials, as expected. Heterogeneous electron-transfer rates were measured for the series in which it was found that some of the derivatives had a faster electron transfer kinetics compared to previously reported benzotriazinyl derivative. Substituent effects are rationalized based on a combination of computation, electronic absorption spectra and spin densities obtained by room temperature EPR. Attempts to gain structural insight from the 6-amino-benzotriazinyl radical lead to SCXRD crystallographic characterization of an 8-amino-functionalized leuco radical, which suggest that steric interactions may inhibit final oxidation to the benzotriazinyl radical. Electronic absorption spectroscopy (UV-vis) and EPR analyses were used to follow the conversion of the leuco to the radical form which occurs slowly over 14–15 hours in the presence of oxygen as an oxidant. Overall, these results provide insights into the role of steric hindrance and planarity in stabilizing the redox processes in these unique radicals and support the potential of functionalized benzotriazinyl radicals as tunable, bipolar electrolytes for RFB charge storage materials with fast charge-discharge kinetics
REGULATION OF INTERSTITIAL CELLS BY HORMONES AND NEUROPEPTIDES: MECHANISMS AND IMPLICATIONS FOR GASTROINTESTINAL MOTILITY
No full textABSTRACT This dissertation investigates the roles and mechanisms of gastrointestinal (GI) hormones and peptides on the myogenic component of intestinal motility. The GI tract is a diverse and unique system that is exposed to a diverse external environment through the lumen. Every meal ingested is a new opportunity for this system to perform a unique set of actions, churning and breaking down solid substances into nutrients and filtering out unwanted or unnecessary components. To achieve this, the GI tract must orchestrate a delicate and highly regulated series of events involving chemical signaling elements of digestion and coordinated smooth muscle events. The myogenic component is composed of smooth muscle cells (SMC), Interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRα+) cells, called the “SIP” syncytium. ICC and PDGFRα+ cells are morphologically distinct interstitial cells that form networks in the circular and longitudinal muscle layers of the tunica muscularis. ICC and PDGFRα+ cells are closely associated with varicose processes of enteric motor neurons and form close networks surrounding the myenteric (Auerbach’s plexus). These networks of cells are electrically coupled through gap junctions and work together to drive precise and coordinated relaxation and contraction of smooth muscle underlying bigger motility motifs, like peristalsis.
It has been well established that GI hormones and peptides influence GI motility. However, research on the effects of GI hormones and peptides on interstitial cells is lacking. Research on this topic could provide a significant bridge to understanding GI motility disorders and diseases that are associated with GI dysmotility. Secretin, Glucagon-like peptide-2 (GLP-2), and calcitonin gene-related peptide (CGRP) are GI peptides that bind to G-protein coupled receptors (GPCRs) present on ICC and PDGFRα+ cells. The first aim in these studies was to establish a functional connection between peptide binding and interstitial cells. All peptides significantly inhibited the force of amplitude of contractions in muscle strip preparations in the small intestine for secretin, and the colon for GLP-2 and CGRP. Additionally, using mice expressing genetically encoded Ca²⁺ indicators (PDGFRα-iCre-GCaMP6f or Kit-iCre-GCaMP6f), we observed significant, cell- and tissue-specific changes in intracellular Ca²⁺ transients and waves in interstitial cells in the presence of the neurotoxin tetrodotoxin (TTX), which blocks neural action potentials and therefore disconnects smooth muscle responses from the enteric nervous system.
In murine and monkey small intestine muscle strip assays, secretin (100 nM) significantly reduced total contractile activity (AUC) and amplitude without affecting contraction frequency. In ex vivo GCaMP imaging, secretin decreased stochastic Ca2+ transients in ICC-DMP, both with and without TTX, while ICC-MY Ca2+ waves were unaffected. Similar reductions in AUC and amplitude, with unchanged frequency, were observed following cAMP elevation via forskolin or 8-Bromo-cAMP (cAMP-analogue). Ca2+ imaging confirmed reduced ICC-DMP activity under these conditions, with no effect on ICC-MY. Using CAMPER-Kit-iCre mice, where the FRET cAMP sensor is exclusively expressed in ICC. Secretin increased FRET signals, confirming cAMP elevation in ICC-DMP. Preincubation with PKA inhibitors predominantly attenuated secretin’s effects, whereas the EPAC inhibitor had partial effects. indicating that secretin actions are mainly mediated via the cAMP–PKA pathway.
Inositol 1,4,5-trisphosphate receptors (IP3Rs) on the endoplasmic reticulum are critical for the spontaneous, stochastic release of Ca2+ in ICC-DMP. To assess this mechanism in secretin responses, we used caged IP3 in ex vivo small intestine preparations from Kit-iCre-GCaMP6f mice. UV uncaging of IP3 during confocal imaging significantly increased Ca2+ transients in control ICC-DMP cells. This response was attenuated in the presence of secretin, indicating that secretin suppresses IP3R-mediated Ca²⁺ release.
Experiments investigating GLP-2 were focused on in the colon due to previously published RNA sequencing data showing the expression of the Glp2r in the murine colon ICC. Functional data showed that GLP-2 at 5 nM and 100 nM significantly inhibited total AUC, amplitude, and contractile events in proximal colon monkey muscle strips with and without the preincubation of TTX, as well as in mouse proximal colon. Confocal Ca2+ imaging of ICC-IM and ICC-MY in the proximal colon showed significant decreases in frequency, area, and spatial spread of Ca2+ events which was also visualized in isolated single cell ICC. The GLP2R is linked to the GPCR-Gαs and therefore as was seen in secretin experiments, we wanted to determine if cAMP was increased in ICC after the activation of the GLP2R. CAMPER-Kit-iCre mouse experiments in the proximal colon ICC-MY, confirmed with immunofluorescence colocalization, showed increases in cAMP levels after the addition of GLP-2 as well as in controls using forskolin.
PKA pathways were shown to crosstalk with PKG and subsequent activation of the IP3R protein regulator, Inositol 1,4,5-trisphosphate receptor-associated cGMP kinase substrate (IRAG). PKG has been shown to phosphorylate IRAG at the ER membrane, negatively influencing the IP3R and preventing the release of Ca2+ from internal stores. Experiments investigating if this pathway is involved in the GLP-2 suppression of Ca2+ signaling in ICC was investigated. Using global IRAG (Mrvi1) knockout mice, the typical inhibitory effects of GLP-2 on colonic contractile events were not significantly affected. Also, In and ICC-specific Mrvi1-KO mice (Kit-iCre-Mrvi1-KO), GLP-2 did not as significantly reduce the total AUC as in controls. GLP-2 is a dynamic GI hormone that may influence ICC function via cAMP signaling as well as in IRAG activation to control Ca2+ handling in ICC and subsequent smooth muscle relaxation of the proximal colon.
The role of CGRPα in colonic motility remains underexplored. The CGRP receptor complex was found to be expressed in PDGFRα+ cells in the colon as seen in previously published RNA sequencing data from fluorescence activated cell sort (FACS) samples. Distal and proximal colon monkey and murine muscle contractions were inhibited in the presence of CGRPα with and without TTX. The CGRPR antagonist, olcegepant, blocked the effects of CGRPα. The small conductance Ca2+ activated potassium channel (K+) subtype 3, (SK3) is exclusively expressed in PDGFRα+ cells in the GI tract. Therefore, with the addition of the SK3 channel antagonist, apamin, the full inhibitory effect of CGRPα seen in controls was blocked in the distal colon and was partially blocked in the proximal colon. Electrical intracellular recordings from distal colon smooth muscles in the presence of TTX showed that CGRPα induced significant hyperpolarization of the resting membrane potential, which was reversed by apamin. In the PDGFRα+-SK3-KO mice, the inhibitory effects of CGRPα were not observed.
Ca2+ imaging of PDGFRα cells showed increased Ca²⁺ activity in PDGFRα-IM and PDGFRα-MY cells after CGRPα in the presence of TTX in both the distal and proximal colon. However, in Ca2+ imaging of ICC, CGRPα was shown to decrease Ca2+ events in proximal colon of ICC-IM and ICC-MY. RNAscope confirmed the expression of the receptor activity modifying protein 1 (RAMP1), which is an integral component that forms the CGRP receptor in PDGFRα cells in the colon. These results indicate that CGRPα bind to receptors on interstitial cells and ultimately leading to smooth muscle relaxation in the colon. This effect can be attributed in part to the activation of the SK3 channels in PDGFRα+ cells.
Collectively, the functional changes observed in ICC and PDGFRα⁺ cells in response to secretin, GLP-2, and CGRP represent significant findings and highlight promising avenues for future investigation
The impact of chain length and GAC characteristics on PFAS thermal degradation
No full textPFAS are anthropogenic “forever chemicals” that are ubiquitous in the environment that have been linked to negative health outcomes. Due to widespread pollution, it is necessary to have an analytical technique that is more affordable, easy, and quick than the standard options. Therefore, the first objective of this thesis was to demonstrate a novel field technique for detection of organofluorine compounds. To meet this objective, a combustion-FTIR system developed in previous work was mobilized to a known PFAS contaminated site to screen nearby soils for organofluorine. This demonstration was effective, and organofluorine was detected in soils in northern Nevada. To remove PFAS from contaminated water, one effective treatment is the use of granular activated carbon (GAC). Spent GAC can then be regenerated through thermal treatment to near-virgin state for reuse in treatment. The thermalregeneration of PFAS laden GAC represents a potential sustainable route to end the cycle of the “forever chemical”. PFAS sorbed to GAC has been shown to thermally degrade at lower temperatures and have increased mineralization,
although the mechanisms behind these catalytic effects is unclear. Therefore, the second objective of this thesis research was to qualitatively understand the changes in thermal decomposition of perfluorocarboxylic acids (PFCAs) caused by GAC surface. To investigate this mechanism, a bench study on thermal degradation of PFAS-laden GAC was conducted. Three well-characterized GAC were spiked with industrially relevant concentrations of four total types of PFAS. The key findings from this thesis are that the presence of GAC, GAC characteristics, and PFAS size have an effect on PFAS thermal decomposition. There were changes in organofluorine products of incomplete destruction, and statistical differences in the amounts of hydrogen fluoride and silicon tetrafluoride generated by sample
G.A. Cohen's Authentic Egalitarianism: A Defense
No full textIn this thesis, I defend G.A. Cohen’s particular brand of egalitarianism which, I argue, aims to restore the authenticity that was seemingly lost with the emergence of the liberal egalitarian theories that gained prominence in the 1970s. From that decade onward, Cohen’s scholarship shifted from a focus on Marxist theory to a focus on egalitarian distributive justice. This decades spanning project found Cohen in dialogue with some of liberal political theory’s strongest proponents; it is through these dialogues that his “authentic egalitarianism” is developed. While the focus of these engagements is centered around traditional concerns of liberal political theory, I contend that Cohen’s deeply analytic approach reveals importance nuances within the debate that many other scholars are historically less concerned with. Consequently, Cohen’s overall project is at times inconsistent. My aim is to clarify what Cohen was striving for by threading together the relevant aspects of these isolated debates and showing how each contributes to the formation of his particular brand of egalitarianism. Cohen’s egalitarianism, I argue, is the best example of what we can consider to be authentic or ideal egalitarianism and ought to be read as the benchmark for what egalitarians should demand